Runway sweeper



G. J. LARSEN 3,284,831

Nov. E5, 1966 RUNWAY SWEEPER 6 Sheets-Sheet l Filed Feb. 1. 1965 ATTO R N SYS Nom l5, 39% G. J. LARSEN 3,2%,83l

RUNWAY SWEEPER Filed Feb. l, 1965 6 Sheets-Sheet 2 INVENTOR @www J. LARSEPJ ATTDRNEYS Nov. l5, 1966 G. J. LARSEN 3,284,833

RUNWAY SWEEPER Filed Feb. 1, 1965 e sheets-sheet s INVENTOR gregorq JLRSEN ATTORNEYS Nov. 15, 1966 G. J. LARSEN 3,284,331

RUNWAY SWEEPER Filed Feb. l, 1965 6 Sheets-Sheetl INVENTDR ATTAQAIFYQ Nov. l5, 1966 G. J. LARSEN 3,284,331

HUNWY SWEEPER Filed Feb. l, 1965 6 Sheets-Sheet 5 INVENTOR Gmqomg J. LARSEN ATTORNEYS Nov. 15, 1966 6.1 LARSEN y 3384,31

RUNWAY SWEEPER Filed Feb. l, 1965 6 Sheets-Sheet 6 Grgwg J. MESE/V ATTORNEYS United States Patent O 3,284,831 RUNWAY SWEEPER Gregory J. Larsen, Roxboro, Quebec, Canada, assignor to Sicard Inc., Ste. Therese, Quebec, Canada Filed Feb. 1, 1965, Ser. No. 429,407 16 Claims. (Cl. 15-82) The present invention generally relates to a runway sweeper, that is to a machine for sweeping snow or dirt off a road, particularly an airport runway. The machine usually includes blowing means for blowing matter loosened by the brush but which has somehow not been brushed aside the road.

More specifically, the invention relates to a new suspension means for mounting the brush assembly on the frame and a new supporting means for supporting the assembly over the ground.

Such machines are already in existence bait have a major disadvantage in that the brush assembly is rigid with the supporting frame so that whenever the carriage, on which the engine and the brush assembly are mounted, is jolted as a result of the machine yhitting an obstacle, the complete machine, including the brush assembly, is affected. Since the obstacle is hit by the wheels of the carriage, located forwardly and rearwardly of the bmsh, the latter responds unnecessarily thereto by rising so that a portion of the road is left uncleaned. Should the road to be swept be somewhat rough, the same upward movement -or rattle lof the brush 'assembly is repeated so that the road surface is not properly cleaned.

It is a major object of the invention to provide a machine of the above type wherein the brush assembly is suspended to the supporting frame in such a manner that it is allowed to move upwardly freely in response to irnperfections of the road surface, these movements taking place independently of the frame. Inversely, any movement of the frame or carriage does not aiect the brush assembly. Consequently, with the suspension of the invention, the brush contacts the road surfacev continuously and wit-h constant pressure so that the road is cleaned completely.

Another important object of the invention lies in the provision of a support for holding the brush at a predetermined relationship with the road surface whereby as the brush wears off, it is Ipossible to lower it from its support a distance corresponding to the worn olf portion.

Still another object of the invention is to provide such a support `as aforesaid with which it will be possible to completelywithdraw the brush from actual Contact with the road surface, whenever desired.

The above noted objects may be obtained with the invention relating to a nunway sweeper having a brush, a rigid supporting member secured to the brush and extending longitudinally thereof to form a brush assembly and a frame, the novelty residing in the provision of a suspension for mounting said assembly to the frame, cornprising: an upper arm articulated at one end to the frame and mounted at the other end on the rigid member to pivot about an axis parallel to said member; a lower arm or structure articulated at one end to the frame, below the articulation of the upper arm to the frame, and mounted at the other end on the rigid member below the pivot connection of the upper arm, to the rigid member to pivot about an axis parallel to said member, and means to apply a lateral thrust on each side of the lower arm, intermediate the ends thereof to cause swinging of the lower arm and brush assembly about an axis extending through the articulations of the arms to the frame.

The invention is also perfected by the addition of means for supporting the brush assembly over the road to be swept and including a support on each side of the suspension, each support comprising: a wheel carrier including 3,284,831 Patented Nov. 15, 1966 an upstanding support bracket; a pair of connecting bars; pivot joints mounting one end of each bar to the bracket and the other end of each bar to the rigid member; the joints forming the four corners of a deformable parallelogram, and an extensible and retractable power ram pivotally connected at one end to one of said bars, intermediate the ends thereof, and at the other end to the rigid member, whereby extension of the extensible ram causes rising and lowering of the brush assembly.

The extensible and retractable'power ram is, by itself, novel and comprises a' cylinder, a fluid pressure operated piston slidable in the cylinder and a rod xed to the piston and slidable in the cylinder; means in said cylinder limiting the stroke length of said piston and means to displace t-he limiting means axially of the cylinder whereby the stroke position of the piston vin the cylinder may vary while lche stroke length thereof remains constant.

More specifically, the piston is an annular member and the ram is provided with a threaded rod mounted for rotation only in the cylinder so as to extend through the annular piston; a nut threaded over the rod whereby rotation of the rod produces displacement of lche nut relative thereto and to said cylinder; co-operating means on the nut and annular piston to limit the displacement of the piston and rod connected thereto relative to the nut and cylinder.

A better understanding of the invention will be afforded by the description that follows having reference to the appended drawings, wherein:

FIG. l is a general perspective view of -a runway sweeper made according to the invention;

FIG. 2 is a top view of the runway sweeper of the invention;

FIG. 3 is a side elevation View of the runway sweeper of the invention;

FIG. 4 is a perspective view of the suspension of the brush assembly to the supporting frame;

FIG. 5 is a partial side elevation view, partially in cross-section, intended to illustrate the above-mentioned suspension;

FIG. 6 is also a partial elevation and cross-sectional view, on an enlarged scale, intended to illustrate the supporting means for thebrush assembly;

FIGS. 7 and 8 respectively are half elevation, half cross-sectional views taken along lines 7-7 and 8-8 of FIG. 9, respectively;

FIG. 9 is a cross-sectional view along line 9 9 of FIG. 7;

FIG. 10 (on the fourth sheet of drawings) is a front elevation view of the blower means of the sweeper of the invention.

Generally, the runway sweeper as shown in FIGS. l, 2 and 3 comprises a wheeled cariage having a rearward engine portion 1 at the forward part of which rises an intermediate vertical frame 3 from which forwardly projects a boom structure S to the forward end of which is mounted thel steering assembly 7 having a trailer hitch member 9 adapted to be secured to a truck supplying the motive power to the runway sweeper. Forwardly of upward intermediate frame 3, is the brush assembly 11 and the supporting assembly 13. A blowing assembly 15 is mounted on the carriage immediately forwardly of the engine portion 1. All these various general assemblies are best identied in FIG. 3.

The suspension which is part of the supporting assembly 13 is, as mentioned previously, a majorobject of the invention and lies in the provision of means interconnecting the brush assembly 11 and the upward intermediate frame 3, adapted to allow movement of brush 17 independently of frame 3.

The said frame 3 comprises two risers 19, connected,

at the upper ends thereof, to the booms 21 of boom assembly 5. In between the two risers 19 are an upper strut 23 and a lower strut 23'. The risers 19 and transverse struts 23, 23', constitute what is termed the upward intermediate frame 3 which, itself, is secured on the forward portion of the chassis 25 of the wheeled carriage.

The brush assembly 11 comprises the previously mentioned cylindrical elongated brush 17, a rigid member 27 extending longitudinally of brush 17, a hood 29, partially covering the upper party of brush 17 and secured to the rigid member 27, and a drive assembly for brursh 17.

The rigid member 27 is also a drive shaft housing and as such is a hollow cylindrical member and contains two drive shafts 31 and 31 (FIG. 4). `The said drive shafts 31 and 31' connect to axial shaft 33 of brush 17 (FIG. 4) through any known transmission means hidden from view in FIGS. 1 and 3 by a guard 35.

Power for drive shaft 31 is obtained through a differential rotated by a telescoping drive rod means 39 connected to differential 37 and to a power take-off 43 through universal joints 41, 41', the power take-off 43 being from the engine of the engine portion 1. It will be noted that the extensible and contractible drive rod 39 passes between the upper and the lower struts 23, 23'.

The suspension of the invention adapted to interconnect the brush assembly 11 and the frame 3 represented in FIG. 4 by transverse struts 23, 23 comprises an upper arm 45 articulated at one end to upper strut 23 and pivoted at the other end to the top of differential 37. The articulation of upper arm 45 to upper strut 23 can be of any known type and it should be understood that by articulation, or articulated joint, is meant a connection between two members whereby one member may be moved, relative to the other member, in any direction and this definition applies to articulation or articulated joint as used in this specification.

In the example shown, the said articulation comprises a vertical pin 47 secured to upper strut 23, the lower end of pin 47 and the corresponding end of upper arm 45 being interconnected by any known ball joint 49.

The other end of upper arm 45 has an eye piece 50 fitting between two upstanding ears 51 of the casing of differential 37, a pin 53 being driven both through ears 51 and eye piece 50 to allow upper arm 45 to swing or pivot about an axis parallel to member 27 which is generally horizontal.

The articulation also comprises a lower arm or structure 55 articulated at one end to the lower strut 23', below the articulation 47, 49 of upper arm 45 and mounted at the other end on the rigid member 27, below the pivot connection 50, 51, 53 of upper arm 45 whereby lower arm 55 can also pivot about a generally horizontal axis or, more precisely, about an axis parallel to the axes of shafts 31 and 33.

More specifically, the lower structure 55 is formed with two spaced legs 57, each pivotally mounted on and between a pair of` spaced parallel links 59 by means of a pin 61. Legs 57 form a triangle at the apex of which is secured a transverse bar 63 the outer ends of which are xed to further bars 65 also connected to the lateral faces of legs 57.

It will be noted that the articulation of structure 55 to the lower transverse strut 23 is through an arrangement similar to articulation 47, 49 of upper arm 45, that is, a vertical pin 47' and a ball joint 49'. Pins 47, 47' are in vert-ical axial alignment.

The two articulations (47, 49-47', 49') and the pivot joints (50, 51 53-59, 61) are so located as to effectively form the four corners of a parallelogram.

A pair of rams 67, preferably iluid actuated, are mounton chassis 25 to apply a thrust at the outer ends of transverse bar 63 of structure 55. A universal joint 69 connects the operating rod of each ram 67 to the outer ends 'of the transverse bar 63.

The centers of the universal joints 69 are in rectilinear alignment with the center of joint 49 to avoid any conversion of the steering forces on the structure 55 into forces tending to increase or lessen the load of the broom assembly, or, conversely to prevent any transfer of vertical forces or components of force from the broom assembly to the carriage assembly or viceversa, through the structure 55.

With the above arrangement, it will be understood that brush assembly 11 will be allowed displacement independently of frame 3 represented by transverse struts 23, 23' because of the pivot connections 50, 51, 53 of upper arm 45 and 59, 61 of lower -arm 55 as well as their respective articulations 47, 49, 47', 49'. For the same reason, selective operation of rams 67 will permit swinging of the brush assembly 11 relative to Iframe 3 about a vertical axis which is also the axis of pins 47, 47.

Because of the articulations of arms 45, 55 to upper and lower struts 23, 23', it will also be understood that Ithe brush assembly 11 and brush 17 may be lifted off the ground unevenly, that is at an angle in relation to the ground in response to an obstruction on the road offset in relation to the suspension.

FIG. 2 clearly illustrates the possibility of angularly displacing the brush assembly 11 in relation to frame 3 by means of selective operation of rams 67.

Thus, means 67 is provided to apply a lateral thrust on each side of the lower arm 55, intermediate the ends thereof, to cause swinging of the said lower arm and the brush assembly 11 about a vertical axis through the articulations 47, 49, 47', 49' of arms 45, 55 to frame 3.

As mentioned previously, means is also provided for supporting the brush assembly 11 over the road to be swept, the said supporting means including two identical supports, each on one side of the above-described suspension. Su-ch a support is particularly illustrated in FIG. 6, and will be seen to comprise a wheeled carrier 71 including a caster assembly 72 and two spaced vertical brackets 73. The lower part of the wheel carrier 71 is la known caster assembly 72 mounted on the said support bracket 73 to swing about a vertical axis in known manner.

A pair of upstanding columns 75 in the form of two spaced parallel plates is secured to shaft housing 27 to extend above and below the said shaft housing.

A pair of upper connecting bars 77 and lower connecting bars 77 interconnect support brackets 73 and columns 75, two-by-two, by means of pivot joints 79, the pairs of bars 77, 77' being xed respectively above and below the shaft housing 27. It will :also be noted that the said bars are so connected that the pivot joints are located at the four corners of a deformable parallelogram in the manner of the upper and lower arms 45, 55, as previously mentioned.

An extensible and retractable power ram 81 is pivotally mounted between columns 75 `and at the upper end thereof, and between the lower bars 77 through a short link 83 rigidly xed to the said lower bars 77. Thus, a triangular ligure is obtained having the two spaced columns 75 as one side, part of the two spaced lower bars 77', up to short links 83, as the second side and power ram 81 as the third side. Because all three apices of the triangle are pivot connections and that power ram 81 is an extensible and retractable member, the said triangle is deformable. Consequently, and with special reference to FIG. 6, whenever power ram 81 is extended the two other sides of the triangle tend to straighten up, including plates 75 each of which is one side of the above said parallelogram, causing brush assembly 11 and particularly brush 17 to rise in relation to Wheeled carrier 71 which, of course, remains rmly on the ground. v Inversely, if power ram 81 is shortened, the two other sides of the triangle (again including one side of the above said parallelogram) tend to make an acute angle with the 'result that brush assembly 11 is lowered. In fact. contraction of lram 81 is brought vabout by gravity alone while extension thereof is obtained and 9.

The fluid pressure operated ram of FIGS, 7, 8 and 9 has a piston with adjustable stroke position but constant stroke length.

It will be seen to comprise a cylinder 85 (connected to plates 75), a fluid operated annular piston 87 provided with the usual circumferential packing 89 in contact with cylinder 85, and a cylindrical rod 91 fixed at one end to piston 87 in any known manner and pivoted, at the other end, to short links 83 as previously mentioned. Rod 91 is o f course mounted in telescopic manner in cylinder 85.

A threaded rod 93 is mounted for rotation only in cylinder 85 and extends through the annular piston. Rotation of threaded 'rod 93 in relation to cylinder 85 may be obtained manually by means of crank 95 with operating knob 97.

A nut 99 is threaded over rod 93 whereby rotation of the rod by means of crank 9S produces displacement of nut 99 relative to cylinder 85, if nut 99 is prevented from rotating by -it-s connection to piston 87, as hereinafter described.

Cooperating means is provided on the nut 99 and on the annular piston 87 to limit displacement of piston 87 and rod 91 Iconnected thereto relative to cylinder 85. The cooperating means just mentioned preferably comprises a radial shoulder 101 at the upper end of nut 99, the said shoulder being formed with a plurality of arcuate guiding grooves 103 (see FIG. 9) at the periphery thereof.

Bolts 105 equal in number to the number of lgrooves 103 are secured on the bore of the annular piston 87 in such a way that the stem of each bolt ts into a groove 103.

As best seen in FIG. 8, each bolt has a head 107 made to abut the lower face of piston 87 and a small inner flange 108, the latter being in sliding contact with the outer surface of nut 99. The bolts 105 extend through a washer 109 lying on top of piston 87 and is screwed into position by means of a nut 111.

With the above description in mind, it will be understood that whenever fluid pressure is applied against the top of piston 87, the fluid being admitted through inlet 113, piston 87 is driven downwardly until washer 109 sits again-st shoulder 101 of nut 99 as clearly illustrated in FIG. 8. Whenever the pressure is released and the brush-assembly 11 is allowed to fall under gravity, cylinder 85 moves downwardly until ange 108 abuts the 'undersurface of shoulder 101. This is the situation illustrated in FIG. 7. The stroke length is therefore the distance between the top surface of ange 108 yand the bottom surface of shoulder 101.

The raising and lowering of the broom is Ahydraulically controlled whereas periodic trimming of the brooms lowermost position is achieved by simple manual adjustment of the stroke limits or .position of the piston 87. It will therefore be appreciated that neither the raising and lowering nor the adjustment of the stroke position of the piston rrequire any amount of ihard manual labor. The adjusting screws 93 beco-me automatically Ifriction looked in either the up 'or the down positions of the lifting ram and there is no tendency or disadjustment to loosen out or wander through the effect of the weight of the broom assembly or of vibrations, and to thereby cause the broom to come in closer and possibly damaging contact with the ground. The provision of means to adjust the lowermost position of the broom is necessitated by the gradual wear of the broom itself.

Positioning of the stroke of piston 87 is obtained by adjustment of nut 99 on rod 93 by `notation of crank 95.

In FIGS. l and 10, are shown certain constructional features of the blowing assembly 15 which is generally composed of a central blower 115 from the outputs of which are connected two ducts 117, generally rectangular in cross-section, directing the air downwardly toward the road pavement. A nozzle portion 119, at the lower end of the straight vertical portion, sends the air to hit the road at a slight angle to thus force dirt or snow toward the side of the road.

Duct 117 is displaceable vertically by means of a lifting assembly com-posed of a connecting V-shaped member 12-1 pivoted at one end to chassis 25 and, at the 'other end, to duct 117, above nozzle portion 119. Motive power is obtained by a hydraulic .ram 1213, the rod of which is pivotally iixed to member 121, intermediate the ends thereof, and to an upstanding yframe of the rear carnage.

rDhe square end of duct 117 is guided against the square end of output 1'27 of blower 115 and held thereagainst by a yoke -129 pivotally secured to both duct 1117 and output 127.

The mouth 137 of nozzle 119 has a closing door 131 hinged, Vas at 133. A longitudinally resilient hook 13-5 is provided on either sides of mouth to retain the door 131 in closed or open posit-ion thereof.

With the above arrangement, both ducts 1|17 may be raised when not in use to prevent them from hitting an obstacle on the road. Door 131 may be `closed if only one duct is required.

Both air nozzles 119 are rotatable through 180 by means of hydraulic motors and are always similarly directed perpendicularly to the center line of the wheeled carriage; both nozzles facing either left or right.

In practice, it has been found advantageous to synchsronize or `couple the actuation of the nozzles directional controls with the means used for the oontrol of the orientation of the broom assembly proper. Through an appropriate selection of valves, it is possible to have both nozzles facing to one side of the Ibroom or to the other side. The nozzles would preferably -be facing to the same side as the broom during normal sweeping operation whereas they would preferably -face to the opposite side when the machine is -used for the pump-ose of blowing the snow away from the lights 'on either side of a runway, an oper-ation generally referred to as blowing of the runway lights. In the Ilatter oase, the broom is not being used and .it is therefore rraised above the road surface and swung out of the way to allow a closer approach of the machine to the lights.

The two air nozzles are in tandem, each using approximately one half of the volume of air that would be used if a single nozzle of twice the cross-section area was used to cover the full width of the swept path. Yet it is more effective since, given equal escape velocities from the nozzles, the drop in the velocity of the escaping air is the same per unit of length, resulting in higher average air velocity across the width of the swept pat-h. T-he trap doors 131 are closed to completely eliminate the air blowing when none is wanted suoh as when operating in the vicinityo'f buildings, parked aircraft and the like.

I claim:

1. In -a .runway sweeper, for `road sweeping, having a rotary br'ush assembly including a rotary brush and a generally horizontal rigid member fixed to said brush longitudinally thereof, said assembly to be mounted on a vehicle frame by means of a suspension adapted to allow vertical movement of ysaid brush, independently of said iframe, caused by imperfections on the lroad to be swept, the invention in the following new combination comprising:

(a) an upper arm articulated at one end to said frame and mounted at the other end on said rigid member generally centrally thereof to pivot about an axis parallel to said member;

(b) a lower arm articulated at one end to said frame, below the articulation of said upper arm to said frame, and mounted at the other end on said rigid member bellow the'pivot connection of said upper arm to said member to pivot about an axis parallel to said member and (c) Imeans to apply a lateral thrust on each side of said lower arm, intermediate the ends thereof, to cause swinging of said lower arm and brush assembly about an axis through said articulations of said arms to said frame.

2. A combination as claimed in claim 1 wherein said articulations and the pivot joints of said members are at the corners of a parallelogram.

3. In a runway sweeper, for road sweeping, having a rotary brush assembly including a rotary brush and a substantially horizontal rigid member xed to said brush longitudinally thereof, said assembly to be mounted on a vehicle frame by means of a suspension adapted to allow vertical movement of said brush, independently of said frame, caused by imperfections on the road to'be swept, the invention in the following new combination comprising:

(a) an upper arm articulated at one end lto said frame and mounted at the other end on said rigid member generally centrally thereof to pivot about an axis parallel to said member;

(b) a lower structure articulated at one end Ito said frame, below the articulation of said upper arm to said frame; said structure being formed at the other end with two spaced legs mounted on said rigid member, below 4and on either sides of the pivot connection of said upper arm to said rigid member, -to pivot about a common axis parallel to said member;

(c) said articulations and pivot connections being at the four corners of a parallelogram, and

(d) means to apply a lateral thrust on each side of said lower structure, intermediate the ends thereof to cause swinging of said lower arm and brush assembly about an axis through said articulations of said arm and structure to said frame.

4. A combination as claimed in claim 3, wherein said last named means comprises a pair of power rams, each pivotally mounted at one end to said frame and, at the other, articulated to said structure on one side of the articulation of said structure to said frame.

5. In a runway sweeper, for road sweeping, having a rotary brush assembly includingl a rotary brush and a susbtantially horizontal rigid member xed to said brush longitudinally thereof, said assembly to be mounted on a vehicle frame by means of a suspension adapted to allow vertical movement of said brush, independently of said frame, caused by imperfections on the road to be swept, the invention in the following new combination comprising: I

(a) an upper arm articulated at one end to said frame and mounted at the other end on said rigid member generally centrally thereof to pivot about an axis parallel to said member;

(b) a lower structure articulated at one end to said frame, below the articulation of said upper arm to said frame; said structure being formed at the other end with two spaced legs mounted on said rigid member, below 'and on either side of the pivot connection of said upper arm to said rigid member, to pivot about a common axis parallel to said member;

(c) said articulations and pivot connections being at the four corners of a parallelogram; p

(d) means to apply a lateral thrust on each side ofsaid lower structure, intermediate the ends thereof to cause swinging of said lower arm and brush assembly about a vertical axis through said articulations of said arm and structure to said frame;

(e) means for supporting said brush assembly over the road to be swept including a support on each side of said suspension, each support comprising:

a wheeled carrier including an upstanding support bracket; a pair of connecting bars; pivot joints mounting one end of each bar t said bracket and the other'end of each bar to said rigid member; said joints forming the four corners of a deformable parallelogram, and an extensible and retractable power ram pivotally connected at one end to one of said bars, intermediate the ends thereof, and at the lother end to said rigid member, whereby movement of said ram causes rising and lowering of said l brush assembly; 4 v 6. In a runway sweeper, for road sweeping, having a rotary brush assembly including a rotary brush and a substantially horizontal rigid member xed to said brush longitudinally thereof, said assembly to be mounted on a vehicle frame by means of a suspensionadapted to allow vertical movement of said brush, independently of said frame, caused by imperfections on the road to be swept, the invention in the following new combination comprising:

(a) anupper armar-ticulated at one end-to said frame and mounted at the other end on said rigid member generally centrally thereof to pivot about an axis parallel to said member;

(b) a lower structure articulated at one end to said frame, below the articula-tion of said'upper arm -to said frame; said structure being formed at the other end with two spaced legs mounted on said rigid member, below and on either sides of the pivot connection of said upper arm to said rigid member, to pivot about a common axis parallel `to said member;

(c) said articulations and pivot connections beingA at the four corners of .a parallelogram;

(d) means to apply a lateral thrust on each side of said lower structure, intermediate the ends thereof to cause swinging of said lower arm and brush assembly about a vertical axis through said articulations of said arm and structure to said frame;

(e) means for supporting said brush assembly over the road toA be `swept including .a support on each side of saidsuspension, each support comprising:

a wheeled carrier including an upstanding support bracket;

an upstanding column secured to and extending above and below said rigid member;

an upper and a lower connecting bar;

pivot joints mounting one end of each bar to said bracket and the other end of each bar to said column, respectively above and below said rigid member; said pivot joints located lat the four corners of a deformable parallelogram, and

an extensible and retractable power ram pivoted at one end to the lower bar, intermediate the ends thereof and pivoted at the other end to said column above said upper bar whereby movement-of said ram causes rising and lowering of said brush assembly.

7. In a runway sweeper, the combination comprising:

(a) a wheeled carriage having an engine and a power 4take-off from said engine;

(b) an upstanding frame on said carriage, forwardly of said take-off;

(c) a brush assembly including an elongated cylindrical rotary brush forwardly of said frame transversely of said carriagefand a driving shaft housing xed to said brush longitudinally thereof;

(d) shafts in said housing for driving said brush into rotation and means operatively joining said-shafts to said power take-off on said carriage;

(e) an upper arm `articulated at one end to said frame and mounted at the other end on and above said shaft housing to pivot about a horizontal axis;

(f) a Ilower structure articulated at one end to said frame, below the articulation of said upper arm to said frame; said structure being formed with two spaced legs mounted on and below said housing to pivot about a common horizontal axis;

(g) said upper arm and lower structure being so c0nnected to said frame and housing that the articulations and pivot connections are at the four corners of a parallelogram;

(h) means to apply a lateral thrust on each side of said lower structure, intermediate the ends thereof, to cause swinging of said -lower structure and brush assembly about a vertical axis through the ar-ticulations of said upper arm and lower structure to said frame, and

(i) means for supporting said brush `assembly over the road to be swe-pt including a wheeled support at each end of the brush assembly.

8. A combination as claimed in claim 7, wherein said first-named means comprises a pair of power rams, each pivotally mounted lat one end to said frame and, at the other end, articulated to said structure on one side of the articulation of said structure to said frame.

9. A combination as claimed in claim 7, wherein each wheeled support com-prises:

a wheeled carrier including an upstanding support bracket;

yan upstanding column secured to and extending above and below said rigid member;

an upper and a lower connecting bar;

pivot joints mounting one end of each bar to said bracket and the other end of each bar to said column, yrespectively above and ybelow said rigid member; said pivot joints located at the four corners of a deformable parallelogram, and

an extensible and retractable power ram pivoted at one end to the lower bar, intermediate the ends thereof and pivoted at the other end to said column above said upper bar whereby movement of said ram causes rising and lowering of said brush assembly.

10. A combination 'as claimed in claim 9, wherein said power lram comprises:

(a) a cylinder, a fluid pressure operated piston slidable in said cylinder and a rod fixed to said piston and slidab-le in said cylinder;

(b) means, in said cylinder, limiting the stroke length of said piston, and

(c) means to displace said limiting means axially of said cylinder, whereby the stroke position of said piston in said cylinder may vary while the stroke -length thereof remains constant.

11. A combination as claimed in claim 9, comprising:

(a) -a cylinder, a fluid pressure operated annular piston slidable in said cylinder and a cylindrical piston `rod fixed at one end to said annular piston and slidable in said cylinder;

(b) a threaded rod Vmounted for .rotation only in said cylinder to extend through said :annular piston;

(c) a non-rotatable nut threaded over said rod whereby rotation of said rod produces displacement of said nut relative thereto and to said cylinder;

(d) cooperating means on said nut and annular piston to limit displacement of said piston and rod connected thereto relative lto said nut and cylinder.

12. A combination as claimed in claim 11, wherein said last-named means comprises:

a radial shoulder on said nut and a plurality of arcuate guiding grooves defined at the periphery thereof;

bolts equal in number to the number of grooves and secured on the bore of `said -annular piston; each bolt having a stem and a head at each end thereof;

said bolts being mounted with the stems thereof in guided position in said grooves and with said radi-al shoulder between said heads to allow movement of said piston between abutting positions of said heads against said radial shoulder.

13. In a runway sweeper having a brush, a rigid supporting member secured to said -brush and extending longitudinally thereof to form therewith ia brush assembly and a frame, a suspension for mounting said assembly to said frame, comprising:

(a) an upper farm articulated at one end to said frame and mounted lat the other end on said rigid member Igenerally centrally thereof to pivot about an axis parallel to sa-id member;

(b) a lower arm artcu-lated at one end to said frame, below the articulation of said upper arm to said frame, :and mounted at the other end on said rigid member below the pivot connection of said upper arm to said housing to pivot about an axis parallel to said member, and

(c) a power ram on said frame and on each side of the articulation of said lower arm to said frame; the rams having operating members connected on either sides of said lower arm, intermediate the ends thereof, :to apply to said 4lower arm lateral forces capable of causing oscillation of said brush and member :about an axis extending through the articulations of the Iarms to the frame.

14. A fluid pressure operated ram having a constant stroke length and adjustable stroke positioning, said ram comprising;

(a) a cylinder, a fluid pressure operated annular piston slidable in said cylinder 1and `a cylindrical piston rod fixed at one end to said annular piston and slidable in said cylinder;

(b) a threaded rod mounted for rotation only in said cylinder to extend through sa-id annular piston;

(c) a non-rotatable nut threaded over said rod Whereby rotation of said `rod produces displacement of said nut relative thereto and to said cylinder;

(d) cooperating means on said nut and annular piston to lim-it the stroke of said piston and rod connected thereto relative to said nut and cylinder.

15. A combination as claimed in claim 14, wherein said last-named means comprises:

a radial shoulder on said nut and a plurality of arcuate guiding grooves defined at the periphery thereof;

bolts equal in number to the number of grooves and secured on the 4bore of said annular piston; each bolt having a `stern and a head at each end thereof;

said bolts being mounted with the stems thereof in guided position in said grooves and with said radial shoulder between said heads to allow movement of said piston between abutting positions of said heads against said radial shoulders.

16. A suspension between a frigid frame and a member movable relative thereto, comprising:

(a) a first arm connected at one end to said frame by an larticulation and at the other end to said member generally centrally thereof by a pivot connection;

(b) a second arm connected at one end to said frame by an articulation and at the other end to said member by a pivot connection allowing relative movement Iabout an axis parallel to the pivot axis of the first arm;

(c) said articulations :and pivot connections being at the four corners of a parallelogram, and

(d) means to apply a lateral thrust on each side of said lower arm, intermediate the ends thereof, to cause swinging of said lower arrn and brush assembly about an axis through said articulations of said arms to said frame.

References Cited by the Examiner UNITED STATES PATENTS 2,548,676 4/1951 Milz et al. 15-82 2,716,965 9/1955 Klamp 92--13 X FOREIGN PATENTS 1,008,999 2/1952 France.

CHARLES A. WILLMUTH, Primary Examiner.

S. E. BECK, Assistant Examiner. 

1. IN A RUNWAY SWEEPER, FOR ROAD SWEEPING, HAVING A ROTARY BRUSH ASSEMBLY INCLUDING A ROTARY BRUSH AND A GENERALLY HORIZONTAL RIGID MEMBER FIXED TO SAID BRUSH LONGITUDINALLY THEREOF, SAID ASSEMBLY TO BE MOUNTED ON A VEHICLE FRAME BY MEANS OF A SUSPENSION ADAPTED TO ALLOW VERTICAL MOVEMENT OF SAID BRUSH, INDEPENDENTLY OF SAID FRAME, CAUSED BY IMPERFECTIONS ON THE ROAD TO BE SWEPT, THE INVENTION IN THE FOLLOWING NEW COMBINATION COMPRISING: (A) AN UPPER ARM ARTICULATED AT ONE END TO SAID FRAME AND MOUNTED AT THE OTHER END ON SAID RIGID MEMBER GENERALLY CENTRALLY THEREOF TO PIVOT ABOUT AN AXIS PARALLEL TO SAID MEMBER; (B) A LOWER ARM ARTICULATED AT ONE END TO SAID FRAME, BELOW THE ARTICULATION OF SAID UPPER ARM TO SAID FRAME, AND MOUNTED AT THE OTHER END ON SAID RIGID MEMBER BELOW THE PIVOT CONNECTION OF SAID UPPER ARM TO SAID MEMBER TO PIVOT ABOUT AN AXIS PARALLEL TO SAID MEMBER AND (C) MEANS TO APPLY A LATERAL THRUST ON EACH SIDE OF SAID LOWER ARM, INTERMEDIATE THE ENDS THEREOF, TO CAUSE SWINGING OF SAID LOWER ARM AND BRUSH ASSEMBLY ABOUT AN AXIS THROUGH SAID ARTICULATIONS OF SAID ARMS TO SAID FRAME. 